1. Field of the Invention
The present invention relates to a method and apparatus for metering and dispensing fluids, particularly fuel. The present invention involves a fluid dispenser which receives fluid from more than one source and which dispenses fluid from one or more outlet, with each outlet dispensing fluid from only one of the fluid sources. In particular, the present invention is useful in a lane-oriented multiproduct fuel dispenser or pump.
2. Description of the Related Art
Fuel pumps and fuel dispensers are known in the art. A fuel pump is a unit which is connected to a source of fuel, and which has housed within the unit a pump for extracting fuel from the fuel source, as well as meters for measuring fuel flow and switches and valves for controlling fuel flow. A fuel dispenser, in contrast, is connected to a source of fuel which contains its own pump. As a result, a fuel dispenser does not require that a pump be housed in the unit, and need only contain the appropriate meters, switches and valves for controlling fuel flow.
Fuel pumps or dispensers are designed in a variety of different configurations. A common type of fuel pump or dispenser, often called a "lane-oriented" pump or dispenser, contains one or more fuel dispensing nozzles on each side of the unit. A lane-oriented multiproduct fuel dispenser or pump contains two or more fuel dispensing nozzles on each side of the pump. Each of the nozzles on each side of the unit is typically used to dispense a particular grade or octane level of fuel. Each side of the unit generally contains a display for displaying the amount and cost of the fuel dispensed, and can also include credit or debit card verification and cash acceptance mechanisms.
An example of a fuel dispenser or fuel pump containing multiple-grade fuel sources and multiple fuel outlets for dispensing from those sources is shown in FIG. 1. Fuel sources 1, 2, 3--which can be in the form of underground or above-ground tanks--are connected to source outlet lines 11, 12 and 13, respectively. Each fuel source 1, 2, 3 typically holds a different grade or octane level of fuel. A fuel pump or fuel dispenser unit 50 is used to dispense fuel from the fuel sources 1, 2, 3. If the unit is a fuel dispenser, pumps 21', 22' and 23' are connected to the source outlet lines 11, 12 and 13 respectively, and are located outside of unit 50. If the unit is a fuel pump, pumps 21", 22" and 23" are connected to the source outlet lines 11, 12 and 13 respectively, and are located within a lower housing 18 of unit 50. The pumps 21', 22', 23' or 21", 22", 23" pump fuel to meters 91, 92 and 93 respectively.
Each meter 31, 32, 33 meters fuel flow from one of the fuel sources 1, 2, 3 to nozzles 61, 62, 63, which dispense fuel from the fuel sources 1, 2, 3, respectively. The fuel pump or fuel dispenser can contain an array of nozzles 61, 62, 63 on both sides of the unit 50 to dispense fuel from either side of the unit 50, in which case there will be meters and nozzles on the opposite side identical to those described above. In the device of FIG. 1, the nozzles 61, 62, 63 can be housed in boots 71, 72, 73, which can contain a put-down switch or lever for initializing the display devices 24, 25, 26 when lifted after the nozzle is removed. The put-down switch or lever is lifted by the operator after the nozzles 61, 62, 63 are removed from the boots 71, 72, 73, and are depressed by the nozzles 61, 62, 63 when they are placed back in boots 71, 72, 73. Nozzles 61, 62, 63 contain actuating levers 81, 82, 83 (in FIG. 1 only actuating lever 83 is visible) to manually control the amount of fuel dispensed and rate of dispensing. Unit 50 can contain an upper structure 15, supported on posts 16, 17, to which fuel hoses 51, 52, 53 for nozzles 61, 62, 63 are connected. Connection lines 41, 42, 43 connect the fuel lines in lower housing 18 to the appropriate fuel hose 51, 52, 53. The unit 50 generally contains suitable display devices 24, 25, 26 for displaying volume and dollar amount of fuel dispensed and other information. The unit 50 also often contains suitable credit or debit card verification and/or cash acceptance modules (not shown).
The large number of meters necessary in the prior art device described above greatly increases the costs of manufacturing the unit, increases the required interior volume of the unit, complicates servicing, and creates more potential leakage points for flammable liquid during both operation and servicing.
Fuel pumps and dispensers are regulated by a number of different governmental agencies in the United States, at both the state and federal level. Regulations promulgated by the Environmental Protection Agency limit the number of potential fuel leakage points which can be exposed during assembly or servicing of a fuel pump or fuel dispenser unit. Furthermore, Underwriters' Laboratories, which tests and approves fuel pumps and dispensers, requires more extensive testing when more potential fuel leakage points are contained within the fuel pump or dispenser. In addition, many state Bureaus of Weights and Measures have regulations governing the amount of variation in octane level that a dispensing nozzle for a particular grade of fuel may have, and governing the amount of fuel that may be purged before this variation is measured. For example, the National Office of Weights and Measures promulgates testing regulations on octane variation in particular octane levels of fuel. This variation is measured after a maximum of three-tenths of a gallon has been purged from the dispensing nozzle.
A variety of different meters have been used in prior art fuel pumps and dispensers. Positive displacement meters, used in many older fuel pumps and dispensers, contain a large internal volume, and are of a relatively large external size. As a result of the size of these meters, it is necessary for the meters to be housed in the lower housing of the unit, which contains a relatively large interior volume. In addition, positive displacement meters need to be manually calibrated, therefore requiring them to be housed at a location in the unit having easy access, such as the lower housing of the unit. Inferential meters, which measure fuel flow according to the speed of fuel through the meter, have a much smaller internal volume than the internal volume of a positive displacement meter, and are less affected by the properties of the particular fuel being metered. In addition, inferential meters can be constructed to be electronically self-calibrating or electronically calibrated.